Emerging research increasingly indicates that the U.S. water supply is widely contaminated with the endocrine disrupting chemical atrazine, but that the Environmental Protection Agency (EPA) is taking almost no action on the threat.

Atrazine is an herbicide widely sprayed on corn fields in the Midwest, and one of the most widely detected groundwater contaminants in the country. Photo: Stephen & Claire Farnsworth.

Atrazine is an herbicide widely sprayed on corn fields in the Midwest, and one of the most widely detected groundwater contaminants in the country. According to an analysis of state and federal records by the Chicago Tribune, atrazine has been detected in the drinking water of a million people in 60 Illinois communities over the past four years. Yet the EPA requires testing for the chemical only four times a year, meaning that short-term spikes of the toxin go undetected — and unregulated.

Special agreements between the EPA and Syngenta, the top manufacturer of the atrazine used in the U.S., have led to limited weekly or biweekly testing for the chemical by 130 water utilities in 10 different states. In 2008, nearly half of these communities in the Midwest alone experienced atrazine levels in their water above the federally imposed limit of 3 ppb (parts per billion) at least once. In Flora, Illinois, levels spiked as high as 30 ppb at one point.

In nine Midwestern communities, atrazine levels averaged higher than 3 ppb for the full year. Yet unless levels higher than 3 ppb are detected during one of the EPA’s four official yearly tests, the agency is helpless to take action. Likewise, contamination detected at other times need not, under the Safe Water Drinking Act, be reported to the public. This has led to a situation where citizens are not only unaware that their water is contaminated, they are never told that an inexpensive home filter could remove the toxin from their water.

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Even the EPA’s “safe” level of 3 ppb, however, may be far too high; studies suggest that atrazine is biologically active in levels as low as 0.1 ppb, mimicking the action of hormones in the body. A recent meta-analysis of 125 studies by researchers from the University of South Florida found that the chemical causes developmental and reproductive defects in amphibians and fish. Another study, conducted by University of California-Berkeley researchers and published in the Proceedings of the National Academy of Sciences, found that small amounts of atrazine lowered testosterone levels and fertility in male frogs. Many of the frogs were chemically castrated or even turned into females.

Prenatal exposure to low levels of atrazine has also been shown to predispose rats to cancer as adults. And according to a 2009 study by researchers from Indiana University, human children conceived between the months of April and July, when atrazine levels in water are highest, were more likely to suffer from nine different kinds of birth defects than children conceived in other months.

“Atrazine … appears to have effects during critical stages of fetal development,” said Suzanne Fenton of the National Institute of Environmental Health Sciences, a former EPA researcher.

Atrazine has been banned in Europe for its contaminating effects on groundwater, and a handful of U.S. states prohibit spraying in certain contamination-prone areas. Yet the EPA’s most recent ruling on the chemical, issued in 2006, endorses its use. The Bush-era ruling was based on a 2003 review heavily funded by Syngenta. Bush administration officials are known to have met with officials from the company at least 50 times before issuing their ruling, including at two industry-dominated panels.

The EPA’s position has drawn the ire of states that have been stuck with regulating the atrazine problem on their own. In 2009, 44 water utilities in the states of Illinois, Indiana, Iowa, Kansas, Mississippi and Ohio sued the federal government to reimburse them for the costs of atrazine cleanup.

Since the 2003 EPA review, a further 100 studies have been published showing health risks from atrazine exposure. The Obama administration is now conducting a review of the EPA’s stance on the chemical.